The Seasonality and Partitioning of Atmospheric Heat Transport in a

Myriad of Different Climate States

I. Introduction II. A simple energy balance model for the seasonal cycle of energy fluxesIII. Dynamical heat transport partitioningIV. Atmospheric heat transport in aquaplanet simulationsV. Atmospheric Heat Transport in Simulations with

Land-Ocean Contrast and TopographyVI. Conclusions

I. Introduction a. The energy budget frameworkb. The dynamical framework

II. A simple energy balance model for the seasonal cycle of energy fluxes

III. Dynamical heat transport partitioningIV. Atmospheric heat transport in aquaplanet simulationsV. Atmospheric Heat Transport in Simulations with Land-

Ocean Contrast and TopographyVI. Conclusions

5.7 PW 5.9 PW

I. Introduction / a. The energy budget framework

ERBE DATA

Zonal and Annual Averaged Energy Flux (global mean removed)

• All signs defined wrt the atmosphere (e.g., negative OLR is an energy flux deficit for the atmosphere)

Surface heat flux = the total energy flux (radiative plus turbulent) through the surface/atmosphere interface

In the annual mean, positive SHF is equal to oceanic heat flux convergence

ASR = Absorbed solar

SHF = Surface heat flux

(-)OLR = Outgoing longwave

MHT = Meridional Heat Transp.

CTEN = (-) Atmos Column tendency

Observed NH

I. Introduction / a. The energy budget framework

ERBE/NCEP

Annual mean of energy budget poleward of 300N

(Departures from global annual mean)

AbsorbedSolar (ASR)

Surface HeatFlux (SHF)

Negative OLR

MeridionalHeat Transport(MHT)

2.2 PW

4.3 PW

1.4 PW

Tropics North Polar Region

7.9 PW

I. Introduction / a. The energy budget framework

(-) OLR

ASR

SHF

MHT

CTEN (-) Atmospheric Column tendency

Zonal and Seasonal Averaged Energy Flux (zonal, annual average removed)

Observed NH

I. Introduction / a. The energy budget framework

ERBE/NCEPDATA

Seasonal Extratropical Energy Budget

I. Introduction / a. The energy budget framework

Temp.Anom. (K)

Meridional Wind Anomaly

STATIONARY WAVES

Mean MeridionalCirculations (MMC)

Transient Eddies (Storm Tracks)Heat Transport

W/m

I. Introduction / b. The dynamical framework

PW

PW

PWPW

I. Introduction / b. The dynamical framework

Partitioning of heat transport from NCEP reanalysis

I. Introduction / b. The dynamical framework

Heat transport partitioning at latitude of maximum heat transport

I. Introduction

II. A simple energy balance model for the seasonal cycle of energy fluxes

III. Dynamical heat transport partitioningIV. Atmospheric heat transport in aquaplanet

simulationsV. Atmospheric Heat Transport in Simulations with

Land-Ocean Contrast and TopographyVI. Conclusions

II. A simple energy balance model for the seasonal cycle of energy fluxes

TROPICS EXTRATROPICS

TS’ BOCE

ASR’

MHT’ = BMHT(T’A,T – T’A,E)

OLR’ = BOLR T’A,E

T’A,E

BCTENTA,E

T’A,T

Primes denote anomaly from global annual mean

Annual mean extratropical energy balance• Global mean energy balance requires:

OLR’ = 0 or T’T = - T’E = ΔT

ΔT -ΔT

TROPICS EXTRATROPICS

•MHT = BMHT2ΔT

•OLR’ = BOLRΔT

•MHT / OLR = 2BMHT/BOLR = 2.3

•Real world ratio is 2.6 (including ocean); we shouldn’t be surprised

ASR’

MHT’

OLR’

II. A simple energy balance model for the seasonal cycle of energy fluxes

II. A simple energy balance model for the seasonal cycle of energy fluxes

Seasonal cycle of extratropical energy fluxes

Asterisks = AGCM simulation

Solid = EBM

Dotted = theoryBased on “B” coefficients

• The seasonal amplitude of extratropical energy fluxes is partitioned into ocean storage (SHF), heat transport (MHT), OLR, and atmospheric storage (CTEN) in the approximate ratio:

lSHF’l : lMHT’l : lOLR’l : lCTEN’l ≈

BOCE : BMHT:BOLR : BCTEN

I. Introduction II. A simple energy balance model for the seasonal cycle of energy fluxes

III. Dynamical heat transport partitioninga. Methodologyb. Spatial and Temporal patterns of variability

IV. Atmospheric heat transport in aquaplanet simulationsV. Atmospheric Heat Transport in Simulations with

Land-Ocean Contrast and TopographyVI. Conclusions

III. Dynamical heat transport partitioning b. Spatial and Temporal patterns of variability

ANNUAL MEAN VERTICALLY INTEGRATED HEAT TRANSPORT

Transient Eddies

Transient Eddies

Stationary Eddies

Stationary Eddies

SEASONAL REGRESSION MAP VERTICALLY INTEGRATED HEAT TRANSPORT

PW

PW

•Units are PW, if the local heat flux existed at all zonal locations

•Seasonal regression takes the zonal mean transient or stationary eddy time series at the latitude of maximum heat transport and regresses it against the spatial map

•OTHER ANAYLSIS- seasonal eofs, inter-annual eofs, interannual variability

I. Introduction II. A simple energy balance model for the seasonal cycle of energy fluxesIII. Dynamical heat transport partitioning

IV. Atmospheric heat transport in aquaplanet simulations

a. Ocean mixed layer depth experimentsb. Longwave emissivity (CO2) experimentsc. Planetary rotation rate experiments

V. Atmospheric Heat Transport in Simulations with Land-Ocean Contrast and Topography

VI. Conclusions

a. Ocean mixed layer depth experimentsIV. Aquaplanet simulations

METHOD: GFDL 2.1 atmosphere (seasonal insolation) coupled to a slab ocean - Vary mixed ocean depth (Dargan)

HYPOTHESIS: Annual mean is unaffected, as the ocean depth increase more seasonal energy goes into ocean storage and the seasonal amplitude of MHT, OLR, and CTEN decrease

Asterisks = AGCM simulation

Lines = EBM simulations

Dotted Lines =B pseudo-steadystate theory

Donohoe and Battisti 2010

b. Longwave emissivity (CO2) experimentsIV. Aquaplanet simulations

METHOD: Vary CO2 from LGM (180 ppm) to 4 times PI (1280ppm) [Dargan]

HYPOTHESIS: - The efficiency of energy export by longwave radiation (BOLR) goes down, in the annual mean and seasonal cycle the ratio of MHT to OLR decreases (infrared opacity)- The efficiency of MHT (BMHT) increases in a warmer world (more moist transport)

b. Longwave emissivity (CO2) experimentsIV. Aquaplanet simulations

Annual Mean Heat Transport

Hea

t T

rans

port

(P

W)

Latitude

QUADPI

180 ppm

c. Planetary Rotation Rates IV. Aquaplanet simulations

METHOD: Vary Earth’s rotation rate from 0.5X to 2.0X the current rotation rate

HYPOTHESIS: With a faster rotation rate, the eddy length scale and efficiency of meridional heat transport (BMHT) will decrease- less heat transport and larger temperature gradient

Dry TransientEddy Heat Transport (1014 W)

Latitude

0.25 Ω

1.0 Ω

EDDY HEAT TRANSPORT AS A FUNCTION OF Ω[Perpetual Annual Mean Insolation, Realistic Topography]

(Del Genio andSuozzo 1986)

I. Introduction II. A simple energy balance model for the seasonal cycle of energy fluxesIII. Dynamical heat transport partitioningIV. Atmospheric heat transport in aquaplanet simulations

V. Atmospheric Heat Transport in Simulations with Land-Ocean Contrast and Topography

a. Land fraction experimentsb. Topography experimentsc. The full gauntlet (realistic climate states)

VI. Conclusions

V. Land-Ocean Contrast and Topographya. Land Fraction Experiments

METHOD: A single extratropical continent with North-South Coastlines and varying zonal width – NO TOPOGRAPHY

HYPOTHESIS: - ENERGETICS: As land mass increases, more seasonal energy goes into the atmosphere, and the seasonal cycle of heat transport increases- DYNAMICS: Zonal heating anomalies induce stationary waves, heat transport partitioning changes, total heat transport (BMHT)?

Solid = EBM simulations

Dashed = Pseudo-steady state theory

V. Land-Ocean Contrast and Topographyb. Topography experiments --- IDEALIZED

METHOD: Aquaplanet with a single idealized mid-latitude topographic feature ofvarying height, meridional location, and zonal width

HYPOTHESIS: - Topography induces stationary wave heat transport - Storm tracks become localized, transient eddy heat transport goes down (seeding?)-Partitioning will change, TOTAL HEAT TRANSPORT?

Mountain Height (km)

Edd

y H

eat

Tra

nspo

rt (

K m

/s)

E

quiv

alen

tly =

0.2

5 P

W

•Dry model, T21

•Newtonian cooling to equilibrium temperature

(Yu and Hartmann, 1995)

V. Land-Ocean Contrast and Topographyb. Topography experiments --- Realistic topography

METHOD: Aquaplanet with flat topography, present day topography, and LGM topography (ICE – 5G, Peltier )

HYPOTHESIS: The partitioning between transient and stationary eddies will change– total heat transport?

Stationary Eddy DRY Heat Transport Transient Eddy DRY Heat Transport

LGM

MODERN

MOD - LGM

Latit

ude 50

5050

50

50 50

-50-50

-50 -50

-50-50

Jan Apr Jul Oct Jan Apr Jul Oct

Jan Apr Jul Oct

Jan Apr Jul Oct

Jan Apr Jul Oct

Jan Apr Jul Oct

PW-2 0 2

PW-1 10

V. Land-Ocean Contrast and Topographyc. The Full Gauntlet (Realistic Climate States)

Method: AGCM (CAM3) simulations of LGM, PI, 4XCO2 forced byprescribed SST and sea ice (from CCSM coupled runs), land ice topography, greenhouse gases, and solar insolation

Hypothesis: (almost) Everything we’ve learned becomes important:1. CO2 experiments2. Land Fraction Experiments (sea ice is like land)3. Topography4. Additionally, the absorbed solar radiation changes, we’ll treat this as a forcing

(CAMILLE LI)

c. The Full Gauntlet (Realistic Climate States)

V. Land-Ocean Contrast and Topography

I. Introduction II. A simple energy balance model for the seasonal cycle of energy fluxesIII. Dynamical heat transport partitioningIV. Atmospheric heat transport in aquaplanet simulationsV. Atmospheric Heat Transport in Simulations with

Land-Ocean Contrast and Topography

VI. Conclusions

QUESTIONS ?